Waking up to driver fatigue

Worker fatigue is one of the most crucial safety issues in the mining industry, particularly for heavy equipment operators. 

According to a study published in 2007 by Caterpillar Global Mining, Viewpoint, perspectives on modern mining, up to 65% of truck haulage accidents in surface mining operations are directly related to operator fatigue. 

As such, the industry has invested heavily in measures to manage drowsiness, including diet programs, training and beneficial rosters and shift programs. 

“However, there has never been a quantitative measure of driver alertness to confirm whether that money was well spent,” Optalert chief executive John Prendergast told Australian Mining

Optalert is a Melbourne-based developer an eponymous system designed to observe the alertness of operators in real-time during their shifts.

“This is the first independently-validated technology available to the market that gives a quantitative measure of the drowsiness of a driver during a shift or journey,” Prendergast said. 

“Optalert DSD uses infrared oculography techniques to measure eye and eyelid movement, which can equate to the level of drowsiness.

“The driver will wear a pair of glasses with two small infrared light emitters inside the frames for the duration of the shift. 

“The emitters create a small cone of infrared light, which measures the velocity of the eyelid at rate of 500 times per second.”

According to Prendergast, this data is processed in an in-cab console that will alert the driver when he is approaching a dangerous level of fatigue. 

“Drivers generally do not realise they have entered into a drowsy state, even though they may be seriously impaired by it,” he said. 

“The best analogy is that no-one remembers falling asleep. 

“However, this technology alerts the driver once that process starts. 

“The driver could get a medium risk indicator when he feels quite fine, but his fatigue levels have actually started to trend upwards.”

Prendergast said level of drowsiness is displayed by a score of zero to 10, with the latter being the most dangerous level of fatigue.

“We have done some studies comparing the levels of impairment caused by drowsiness to the impairments that result from alcohol consumption,” he said. 

“We found the level of impairment for a score of five on our system is similar that of a blood alcohol reading of 0.05.” 

The data can also be passed to a minesite control centre and run through a web-based profiling service. 

This could be used to plot the times when individual drivers are most at risk from drowsiness. 

“This allows companies to focus money in early preventative measures like training, education and diet, rather than the broad-brushed approach they have been using,” Prendergast said. 

However, Prendergast said the initial studies using the technology have shown how driver fatigue can strike at any time of the day. 

“The data does not really show particular periods which are universally risky; it is not as neat and tidy as that,” he said.

“This largely because most companies make the perfectly reasonable assumption that anyone starting work is fit for that task. 

“But in reality, this fitness actually depends on so many other factors that it cannot be guaranteed. 

“The driver might turn up on Monday morning in absolutely perfect condition and the system would show that. 

“But he could go home, have a terrible night’s sleep and fluctuate in and out a high-risk window during the next day’s shift.” 

The technology is therefore designed to help the driver and management react to the state of fatigue. 

“The system works best when a company has a mature fatigue policy in place and their drivers know what to do when they do feel tired,” Prendergast said. 

“This can involve taking a break or even physical activity like stretching; some mining companies encourage workers to have a nap in their cab.

“People often transit in and out of drowsy states and the simplest activity can bring them out of it. 

“A simple telephone call from the control centre could snap you out of it.” 

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